Golden-progression-util is a project mainly written in COFFEESCRIPT and JAVASCRIPT, it's free.
gpu = require 'golden-progression-util'
arc1 = 412
arc2 = gpu.next_arc arc1
console.log arc2 # 123
# suppose we have the following geometric properties for the square with arc1
left1 = 0
top1 = 0
side1 = 10
# we can easily calculate the geometric properties for the next square
# in the progression ( which has an arc equal to arc2 )
[left2, top2, side2] = gpu.next_square arc1, left1, top1, side1